The proposed research focuses on structure-function relationships in complex regulatory enzymes. These relationships are examined by kinetic means as well as by changes in molecular and physical properties. The specific aims of the work include investigation of subunit interactions, enzyme-enzyme interactions, and the investigation of kinetic mechanisms particularly related to a model dehydrogenase reaction and isomerization processes which occur in binary and ternary enzyme complexes. These problems are approached experimentally using the bovine liver glutamate dehydrogenase, rabbit muscle phosphofructokinase, adenylic deaminase and myosin, heart cytoplasmic and mitochodrial malate dehydrogenases and aspartic amino transferases. Kinetic theory in relation to coupled enzyme systems and allosteric behavior in multisubstrate enzymes will continue in conjunction with computer programs developed for simulating and analyzing kinetic data.